Lights dimming

Went out last night in my disco and the lights were dimming and every now and again in the day when I flash someone the head light cuts out, any idea what could be wrong?

The dimming on it's own I would say sounds like a charging issue, however if they cut out too I am more inclined to think there is a bad earth somewhere which isn't up to carrying the load.

Yep if batteries charged its a bad connection, sometimes the connector on the headlight just needs pulling off and pressing back on a few times (had same prob on my motorhome and was dirty / corroded contacts).
Could also be the relay starting to fail (waters got inside and is corroding the contacts)

sounds like the same prob i had on my 200tdi. needed a whole new stalk because of this prob because something shorted due to power of my spots and headlights when on fullbeam

new stalk and do the relay mod in the FAQ section.

Just looked at the earth terminal cable it's earthed on the chassis but it has come of from the engine so gonna buy another earth cable to earth the engine out and see if that cures it.

Was it the same with both headlamps? as each is on it's own circuit the supply and earths are separate the common point is the switch or the dim-dip relay.

Both lights were dimming at night and the head unit turns off when I flash high beems I also forgot to say that the heater blows for a while then stops and then starts again.

Oh and the rev counter drops now and again

sounds like alternator has an intermittent earth circuit.